1. Field of the Invention
The present invention relates to a resister ink and a pattern formation method, and particularly, to a register ink which has an enhanced acid-resistance due to an addition of a silane coupling agent and can prevent a defect caused by a liquation of remnants, and a pattern formation method using the same.
2. Background of the Invention
A display device, especially, a flat panel display device, such as a liquid crystal display (LCD) device, is driven by employing an active device, e.g., a thin film transistor, at each pixel. This type of driving method of the display device is usually referred to as an active matrix driving method. The active matrix driving method is achieved such that the active device is disposed at each of pixels, arranged in a matrix configuration, thus to drive the corresponding pixel.
FIG. 1 shows an active matrix type LCD device. The LCD device with the structure shown in FIG. 1 is a thin film transistor (TFT) LCD device which employs TFTs as the active device. Referring to FIG. 1, the TFT is located in each pixel of the LCD device having N×M pixels disposed vertically and horizontally. Each of the TFTs is formed at an intersection between a gate line 4 to which a scan signal is applied from an external driving circuit and a data line 6 to which an image signal is applied therefrom. The TFT is provided with a gate electrode 3 connected to the gate line 4, a semiconductor layer 8 formed on the gate electrode 3 and activated responsive to a scan signal applied to the gate electrode 3, and a source/drain electrode 5 formed on the semiconductor layer 3. A display region of a pixel 1 is provided with a pixel electrode 10, which is connected to the source/drain electrode 5 so that an image signal is applied thereto via the source/drain electrode 5 in response to the activation of the semiconductor layer 8, thereby operating a liquid crystal (not shown).
FIG. 2 shows a structure of the TFT located in each pixel. As shown in FIG. 2, the TFT includes a substrate 20 formed of a transparent insulating material such as glass, a gate electrode 3 formed on the substrate 20, a gate insulating layer 22 laminated over the entire substrate 20 located on the gate electrode 2, a semiconductor layer 6 formed on the gate insulating layer 22 and activated upon a signal being applied to the gate electrode 3, a source/drain electrode 5 formed on the semiconductor layer 6, and a passivation layer 25 formed on the source/drain electrode 5 for protecting a device.
The source/drain electrode 5 of the TFT is electrically connected to the pixel electrode formed in each pixel. Accordingly, when a signal is applied to the pixel electrode via the source/drain electrode 5, a liquid crystal is driven so as to display an image.
As stated above, the active matrix type display device, such as the LCD device, has pixels each having several tens of nanometers in size. Hence, the active device, such as the TFT, disposed within the pixel, should be minutely formed to be several nanometers in size. In particularly, the increase in demands on the high definition display devices such as high definition television(HDTV) requires that more pixels be disposed within the same scale screen, accordingly active device patterns (including gate line patterns and data line patterns) disposed within each pixel also have to be more minutely formed.
In the meantime, in order to fabricate the active device such as the TFT in the related art, patterns or lines of the active device have been formed by a photolithography using an exposure system. However, the related art pattern formation has to adopt a photolithography by an exposure process performed after laminating a photoresist on a layer to be patterned. Here, since the exposure system has a limited exposure area, the photolithography should be performed by splitting a screen in order to fabricate a large display device. Therefore, upon the photolithography process for the split areas, an accurate position alignment of the exposed areas is difficult and also the photolithography should be repeated plural times, resulting in lowering of productivity.
In order to obviate such problems, a printing method has been recently proposed in which a resist pattern is formed by printing a resist ink directly on an etching target layer, such as a metal, by use of a roll, and then the etching target layer is etched with an etching solution under a state of masking the lower etching target layer with the resist pattern.
The printing method is implemented such that a resist ink with a desire form (i.e., a form depending on a pattern shape) is formed on a print roll, which is then rolled on a substrate so as to transcribe the resist ink thereon, thereby forming a resist pattern. However, the etching by the related art printing method has the following problems.
Typically, a photoresist is photocrosslinked as light is irradiated with a photo initiator being added because patterns are formed by exposure process, while the printing method derives the crosslink by a backing process other than the photocrosslink. However, in the baking process, if part of components remains without being crosslinked after being baked, when an etching solution is added, remnants are liquated, thereby causing damage such as a generation of a pin hole in a resist link. The damage on the resist ink may cause a defect upon etching the etching target layer. Further, the resist ink may be peeled away by the remnants during wet etching, thereby exposing a metal layer. Consequently, the etching solution even etches the exposed metal layer. As a result, a width of a pattern may problematically be narrower than a preset width or even a short-circuit may occur in the pattern.